Apparatus for adjusting turbine guide vanes and the like

ABSTRACT

Apparatus for adjusting a movable member, for example a guide vane for a gas turbine engine, including an actuating cylinder, and an actuating piston slidably disposed in said cylinder, with one of the cylinder and piston connected in a direct drive linkage for moving the guide vane. A control valve is provided for controlling the opening and closing of respective inlet and exhaust ports leading to a control chamber which effects movement of the actuating piston. This control valve includes a control valve member having one end face acted upon by a fluid control pressure and one arm of a two armed elastically loaded lever contacting the control valve member to force the same against the fluid control pressure. The other arm of the lever includes a roller and is in contact with a predetermined generating line provided in a cavity of the actuating piston such that movement of the actuating piston changes the resistance to movement of the control valve member exerted by way of the lever, whereby a precise and accurate positioning of the actuating piston, irrespective of the reactive forces acting on the actuating piston is obtained.

United States Patent 11 1 Greune et al.

1 APPARATUS FOR ADJUSTING TURBINE GUIDE VANES AND THE LIKE [75]Inventors: Christian Greune, Furstenfeldbruck;

Hilbert Holzhauer, Stetten, both of Germany [73] Assignee: MotorenundTurbinen-Union Munchen GmbH, Germany [22] Filed: July 8, 1974 I21] Appl.No.: 486,441

FOREIGN PATENTS OR APPLlCATIONS 1,019,173 2/1966 United Kingdom [4 1Sept. 16, 1975 Primary Examiner-Henry F. Raduazo Attorney, Agent, orFirm-Craig & Antonelli ABSTRACT Apparatus for adjusting a movablemember, for example a guide vane for a gas turbine engine, including anactuating cylinder, and an actuating piston slidably disposed in saidcylinder, with one of the cylinder and piston connected in a directdrive linkage for moving the guide vane. A control valve is provided forcontrolling the opening and closing of respective inlet and exhaustports leading to a control chamber which effects movement of theactuating piston. This control valve includes a control valve memberhaving one end face acted upon by a fluid control pressure and one armof a two armed elastically loaded lever contacting the control valvemember to force the same against the fluid control pressure. The otherarm of the lever includes a roller and is in contact with apredetermined generating line provided in a cavity of the actuatingpiston such that movement of the actuating piston changes the resistanceto movement of the control valve member exerted by way of the lever,whereby a precise and accurate positioning of the actuating piston,irrespective of the reactive forces acting on the actuating piston isobtained.

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APPARATUS FOR ADJUSTING TURBINE GUIDE VANES AND THE LlKE BACKGROUND ANDSUMMARY OF THE INVENTION The present invention relates to appratus foradjusting a movable member, for example turbine guide vanes and thelike. The present invention is more specifically related to an improvedactuator which has an actuating piston slidable in an actuating cylinderin accordance with a predetermined characteristic in response to fluidpressure acting on said piston.

Previously contemplated fluid pressure responsive actuators of thejust-mentioned category utilize a cam disk for maintaining and givingthe predetermined characteristic. (See British Pat. No. 1,055,319). Adisadvantage of such previously contemplated actuator is that additionalmeans are required to operate the cam disk by means of a hydraulic orelectrical input signal in an automatically occurring process. A furtherdisadvantage of such actuators is seen in that an actuating rodextending through a control chamber between the actuating piston and acontrol valve for fluid supply to said actuating piston, in parallelwith the control valve for endwise movement imparted to it by the camdisk against the force of a spring and carrying a rotatably mountedtwo-armed lever leads through the housing of the hydraulic actuator.Such a lead-in of the lever through the housing is difficult to sealoff, causes friction, and poses further design problems related tohydraulic thrust imposed on the actuating rod.

The present invention overcomes the above mentioned disadvantages byproviding a pressure medium operated piston-cylinder actuator whichachieves respective intended positions of the actuatingpiston with greatprecision and relatively moderate complexity of the actuating means.According to the invention, the previously contemplated actuating rod,the lead-in through the actuator housing, and the cam disk bearing thecharacteristic are all eliminated and a hydraulic input signal issupplied to the hydraulic actuator directly and in the absence ofintervening mechanical links. In this way, the characteristic curve forchanging the control force on the control valve in dependence upon therelative position of the actuator piston and cylinder can be constructedin a simple manner to be linear, nonlinear, or not uniformly linear.

More specifically, the present invention contemplates apparatus forimparting adjusting movements to a movable member, such as a linkagemember in an actuating train for a guide vane on a vehicular gas turbineengine, which apparatus includes an actuating cylinder, an actuatingpiston slidably disposed in the cylinder, means for connecting one ofthe actuating cylinder and actuating piston to a movable member formovement therewith, a control chamber communicating with a first face ofthe actuating piston such that supply of fluid under pressure to thecontrol chamber effects movement of the actuating piston in a firstdirection and drainage of fluid from the control chamber permitsmovement of said actuating piston in a second direction opposite thefirst direction, control chamber inlet means for communicating fluidunder pressure to the control chamber, control chamber exhaust means forexhausting fluid from the control chamber, a control valve forcontrolling the opening and closing of the control chamber inlet andexhaust means, said control valve including a control valve member actedupon in one direction by a fluid control pressure and in the otheropposite direction by a control biasing force, the actuating pistonincluding a cavity bounded in part by a generating surface which isspaced from the centerline of said actuating piston by varying amountsalong the length of said actuating piston, and interconnecting means incontact with both the control valve member and the generating surfacefor efiecting changes in the control biasing force as a function of theposition of the actuating piston along the travel path thereof in theactuating cylinder. According to a further aspect of the invention, theapparatus just described is constructed such that the cavity forms partof the control chamber, wherein a second face of the actuating pistonwhich faces oppositely of and is smaller than the first face iscontinuously communicated with the fluid under pressure supplied to thecontrol chamber inlet means, wherein the fluid under pressure is ahydraulic fluid, wherein the interconnecting means is a two-armed leverhaving one arm thereof in contact with the control valve member and theother arm thereof in contact with the generating surface, and whereinthe twoarmed lever is supported intermediate the arms thereof at a partfixed with said actuator cylinder.

In preferred embodiments of the invention, the actuating piston, whichis constructed as a differential area piston, will not move so long asthe force of control pressure acting on said end face of said controlvalve member is equal to the force of flexural preload of the leveracting on the control valve member in the axially opposite direction.Said preload of the lever varies with the position of the actuatingpiston as a result of the form of the generating line. When a changeoccurs in control pressure the resulting discrepancy between said twoforces causes the control valve member to move away from its shut-offposition in one or the other axial direction. This movement of thecontrol valve member either pressurizes the larger face of the actuatingpiston in the control chamber and the actuating piston is moved in itsone axial direction, or exhausts the control chamber and the actuatingpiston is moved in the opposite direction while the control chamber isbeing emptied accordingly. Movement of the actuating piston, due to theform of the generating line, causes the force of lever preload to changeuntil equibrium is achieved with the new force of control pressure,which returns the control valve to its shut-off position. The actuatingpiston comes to rest in very precisely the intended position.

With the apparatus of the present invention, the actuating pistontravels, as a function of control pressure, an intended distance whichis independent of the magnitude, direction and change in load resistanceacting on the actuating piston. In use for adjusting turbine engineguide vanes, the load resistance has its origin especially in the gasforces acting on the guide vanes. The actuating means of the presentinvention is relatively simple and free from complexity. Forces arebalanced one against the other and a lead-in in the housing iseliminated together with its above-mentioned disadvantages. Due to thesimplicity of design, the actuating means of the present invention canbe a robust construction. The actuating means of the present inventionis also practically insensitive to vibrations, which prevents wear onits parts and noise.

The actuating accuracy of the hydraulic actuator of the presentinvention can be improved by increasing the inclination of thegenerating line relative to the centerline of the actuating piston.Depending upon the desired characteristic acceleration and decelerationof the member being adjusted (e.g. turbine guide vane), the generatingline may be curved over part of all of its length or it may angleoff ina straight line, according to the present invention. In the case ofnon-uniform linearity between the pressure signal and the stroke of theactuating piston, a preferred embodiment varies the inclination of thegenerating line relative to the centerline of the actuating piston toeffect drive, neutral and deceleration ranges respectively, where moreparticularly the inclination is relatively great at first (drive range),then relatively small, and finally relatively great again (decelerationrange). The actuating accuracy is thus made relatively great in thedrive range and in the deceleration range, as it would indeed bedesireable in use. In between the accuracy of actuation, and with it theinclination, may well be less. The gradient of the generating line ispreferably steeper in the drive range than in the deceleration rangeaccording to the present invention.

In a preferred embodiment of the present invention a control cylinderinlet, with a pressure line connecting to it, communicates with thatportion of the control cylinder chamber adjacent to the control pressureend face of the control valve member through a restrictor duct. Thislast-mentioned portion of the control cylinder chamber communicates witha control nozzle, for controlling the magnitude of the control pressurearranged ahead of which is a control member loaded by a variableelectromagnetic force for controlling the control nozzle. The restrictorduct is preferably located in the control valve member but mayoptionally be pro vided also in the valve body. The control valve thuslikewise functions also as a pilot restrictor for the pressurization ofthe control oil or for the control pressure circuit. For pressurizationof the control oil, hydraulic medium flows from the inlet of the controlcylinder, through the restrictor duct, into said portion of the con'trol cylinder chamber and into a control pressure chamber surroundingthe area of the control nozzle inlet, in which spaces the hydraulicmedium backs up until it attains the control pressure at which the forceof control pressure acting on the control member and the electromagneticforce are in equilibrium. In this balanced condition the control nozzleis in a somewhat open position and allows control pressure medium toescape from it continuously. When a change occurs in the electromagneticforce, a new control pressure results, the force of which on the controlvalve is equal to the new electromagnetic force. The continuous flow ofmedium through the restrictor duct and the control nozzle also serves tocool the actuating means of the hydraulic actuator.

The actuating means of the present invention can be used, e.g., forvarying the blade angle of the guide vanes of an inlet stator of a powerturbine of a twospool gas turbine engine.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawings which show, forpurposes of illustration only, several embodiments in accordance withthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 of the accompanyingdrawings are longitudinal sections illustrating an embodiment of theactuating means assembled in accordance with the present invention forvarying the blade angle of gas turbine guide vanes of a vehicular gasturbine engine, where FIG. I shows the hydraulic actuator with itsactuating piston and control valve in a section taken at theircenterlines (longitudinal section) and FIG. 2 shows in longitudinalsection the transducer furnishing the control pressure;

FIG. 3 of the drawings illustrates an alternative preferred embodimentof the control valve and body in a section taken at the centerline ofthe control valve and at right angles to the centerline of the actuatingpiston; and

FIG. 4 of the drawings illustrates a further alternative preferredembodiment of a control valve body and valve as seen in partiallongitudinal section from FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS The actuating means of FIGS. 1 and2 essentially comprise an actuator (FIG. 1) exhibiting a cylindricalactuating piston 10 and a cylindrical control valve 11, and a transducer(FIG. 2) in the form of an electromagnetic device for motivating acontrol member 46 for a control nozzle 21, where the member 46 is undera magnetic force which varies proportionally to the variation in inputvoltage arrowheads 88 to a solenoid 47.

The centerline 30 of the actuating piston and the centerline 36 of thecontrol valve 11 are at right angles to one another and in the plane ofprojection. The actuator housing essentially consists of a cylinder 12accommodating the actuating piston 10, and a cylinder head 13accommodating the control valve 11. The cylinder 12 and its head 13 arefixedly connected, more particularly screwed, one to the other, or theymay altematively be a solid construction. The cylinder head 13 isessentially about centerline 30. The cylinder head 13 and the actuatingpiston 10 are each fitted with a lug 63 and 64, respectively. Lug 63,which stiffens the cylinder head 13 to resist distortion constitutes afixed point of the actuator, while lug 64 connects this is not shown toa guide vane actuating ring gear via further connecting members andabsorbs the load. See the above-mentioned British Pat. No. 1,055,319 fora showing of a system with guide vanes and mechanism for adjusting same.

One face 14, of the actuating piston 10 is half the size of another face15, part of which face 14 is formed by an axially arranged centralcavity 16. An oil pump, details omitted on the drawing, supplies oilpressure p to face 14 through a pressure line (arrowhead 89) extendingfrom the pump. Installed in pressure line 60 is a pressure limiter valve44 set at the maximum allowable oil pressure. The cavity 16 and theadjacent members in the interior of the actuator form a chamber which isfilled with oil and closed ofi by control valve 1 1. The actuatingpiston 10 is at rest in the position illustrated in FIG. 1.

In this control chamber a doublearmed lever 20 is carried on knife-edgeon a bearing member 19 of a cylindrical cover fixedly connected to headI3. The lever 20 extends through an opening in the cover and can beloaded flexurally in that its upper arm as seen in the drawing consistsof a relatively short and relatively stiff portion. Attached to saidupper arm, by riveting or otherwise, is a relatively long leaf spring 23with a ball and socket 25 or alternatively a sliding member or a rollerat its extreme end. This leaf spring 23 is disposed fully within cavity16 as illustrated. Ball 25 rests against the generating line of thecavity 16, whereas the end of the other arm of lever 20 forks around acentrally arranged cylinder control valve member 51 flattened on bothsides at that point. The one visible (FIG. 1) of the two flattenedlands, which are arranged symmetrically with respect to the plane ofprojection, is indicated with the numeral 35. The two parts of the fork,which approximately takes up the outer half of said arm, contact withtheir rounded ends with the two equidirectional faces 39 of the twolands 35 in the longitudinal plane 40 of the control valve 11 at rightangles to the plane of projection. [n this manner a balance undisturbedby tilting moment is achieved between the spring force of lever 20 and aforce acting axially on control valve 11 of a control pressure p of theoil.

The lever 20 or its leaf spring 23 are preloaded by this force ofcontrol pressure. The control pressure p comes to bear in a portion 41of the control cylinder chamber, in a hole of an adjacent member, in aconnecting line 43 for which see FIG. 1, and FIG. 2 for its connectingportion and in a control pressure chamber 45 of the transducer. Controlpressure p acts on a control pressure end face 48 of the control valve11. With the respective force of control pressure being equal to thepreload on the lever; the control valve 11 is at rest.

The generating line or surface of the cavity 16 is formed to suit anintended or given characteristic, i.e., to suit the intended travels ofthe actuating piston, ultimately the desired change in blade angle ofthe guide vanes, as a function of said input voltage, or the controlpressure p proportional to it or the magnetic force. The characteristicschematically depicted to the right of the actuating cylinder 12 in FIG.1, includes two relatively flat and short straight lines, line 26 fordrive range A s and line 28 for deceleration range As of the guidevanes, and a relatively steep and long straight intermediate line 27 foran intermediate range with a neutral position s of the actuating pistonor of the guide vanes. The full travel of the actuating piston isindicated with the symbol A Accordingly, the generating line consists oftwo short, straight and, with respect to centerline 30, relatively steepruns 31, for drive range A SF, and 33, for deceleration range A s and ofa relatively flat and long straight intermediate run 32. The ball 25rests against the straight run 33 in the illustrated rest position.

The control valve 11 and the cylinder head 13 are simple constructions.The control valve 11 exhibits, at each end of valve member part 51, acylindrical member part 49 and 50, respectively, having a diameterlarger than that of valve member 51 and, at the level of the respectivesaid end, an inlet control edge 52 and an outlet control edge 53,respectively. The control cylinder 54 and the cylinder head 13respectively exhibit an annular inlet slot 55 controlled by inlet edge52 and an annular outlet slot 56 controlled by outlet edge 53. Thisinlet connects to a pressure line 61 diverted from pres sure line 60.The annulus 57 surrounding the valve memmber 51 forms part of thecontrol chamber. The

distance of the edge 52 and 53 from one another is equal to that betweenthe two inner controlling edges of annular slots 55 and 56.

The pressure line 61 connects to an inlet duct 62 which in turn connectsto annular inlet slot 55. The annular inlet slot 55 communicates withportion 41 of the cylinder chamber via an annular slot, an axiallyarranged central hole and an axially arranged central restrictor port 42of the control valve 11 or the valve member 49, causing pressure oil toflow from the annular inlet slot 55 into portion 41 of the cylinderchamber for duty as control pressure oil. The force of control pressureof the oil acting on control member 46 (FIG. 2) is in balance with themagnetic force applied by solenoid 47, solenoid 47 being of knownconstruction. Control nozzle 21 is always in a somewhat open positionand allows oil to drain continuously into an oil reservoir not shown onthe drawings, as indicated by arrowhead 90. The extent of opening ofcontrol nozzle 21, and hence the value of control pressure p iscontrolled by voltage input 88. The control pressure p is thereforealways smaller than the oil pressure p prevailing in the annular inletslot 55.

With reference now to FIG. 2, it is noted that the control pressure pacts, in control pressure chamber 45, on a diaphragm 17 and, via aconnecting duct 38 in a control pressure chamber 22, on a diaphragm 18the effective portion of which is somewhat smaller than that ofdiaphragm 17, so that the resulting force of oil pressure on controlmember 46, which is in fixed and oiltight connection with diaphragms 17and 18, is very modest and therefore requires not more than an equallymodest magnetic force and, thus, only a relatively small-sizedelectromagnetic means.

Annular outlet slot 56 communicates with an outlet duct 29 from which adrain line 37 leads to an oil reservoir not shown on the drawings, asindicated by arrowhead 91. A gland leakage line (dashed line at rightside of FIG. 1) likewise discharges into this reservoir. In order toattenuate axial vibrations of control valve 11, this outlet of thecontrol cylinder and a portion 59 of the control cylinder chamberadjacent to the end face 58 of control valve 11 are in communicationthrough a damping duct formed in valve body 13 by a slot 24 extending inparallel with centerline 36.

When the input voltage 88 falls off, the magnetic force is reduced, thecontrol nozzle 21 is opened wider and the control pressure p is thusreduced until balance is established between the associated force ofcontrol pressure on control member 46 and the reduced magnetic force.When the input voltage is raised, the process is reversed. The oilpressure p in the annular inlet slot 55 is the maximally attainablecontrol pressure p for the reasons noted above. Any reduction or rise incontrol pressure p causes the control valve 11 to move from its shut-ofiposition in its one axial direction, or opposite it, to establishcommunication between the annular inlet slot 55 and the cavity 16 orbetween it and the annular outlet slot 56. This causes face 15 to comeunder oil pressure p and the actuating piston 10 to be moved away fromcontrol valve 1 1, or actuating piston 10 to be moved in the oppositedirection as the control chamber is being emptied accordingly. In theprocess of movement of actuating piston 10, the fonn of the generatingline causes the ball and socket 25 to travel farther apart fromcenterline 30 or closer to it, or the preload on the lever to fall orrise until balance is established with the new force of controlpressure, thus pushing control valve 1 1 back to its shut-off position.The actuating piston 10 therefore comes to rest very accurately in theposition that relates to control pressure p or the input voltageproducing it.

The control valve 79 and the cylinder head 78 shown in FIG. 3 areequally simple constructions. This cylindrical control valve 79, hereshown in its shut-off position, exhibits a centrally arrangedcylindrical valve member 70 having an inlet control edge 71 at its oneend and an outlet control edge 72 at its other. The control chamber(cavity 16 and portion opening to the control valve are described inFIG. 1 above) leads, with a cylindrical duct or opening 73, to the valvemember 70 where it is as wide as the distance 74 between control edge 71and control edge 72. The diameter of the duct 73 is equal to thisdistance 74. The two fixed edges are formed by the wall of duct 73 andthe wall of a control cylinder 75. The control cylinder 75 exhibits,outside the valve member 75 axially, an uncontrolled inlet duct 76 onthe one axial side and an uncontrolled outlet duct 77 on the other. ThisFIG. 3 control valve operates in the FIG. 1 system in a manner asdescribed above for control valve 11.

In accordance with the arrangement in FIG. 4 a control valve 11 isseated for sliding movement in a bushing 80 having a controlled inletslot 81 and a controlled outlet slot 82 and being seated in a cavity 84of the actuator housing, here of cylinder head 83. The bushing 80 isconnected, at the seating port of cavity 84, with cylinder head 83 for afixed position axially but at a distance radially from the cavity 84.When a load is applied at a lug 64 (see FIG. 1) with the actuatorhousing secured in an abutment lug 63 (see FIG. 1) of cylinder head 83,the forces occurring in the cylinder head 83 will not affect the controlvalve 11 if use is made of this bushed design. This P16. 4 arrangementotherwise operates as described in connection with FIG. 1.

Sealing rings, here represented by O-rings, arranged between the bushing80 and the cavity 84 serve to seal differently pressurized chambers onefrom the other. So that bushing 80 may readily permit insertion axiallyin cylinder head 83 the outer diameter of the bushing and the innerdiameter of the cavity are widened counter the direction of insertion inseveral steps. As a result the O-rings will be seated, as shown, betweenthe respective bushing sections and cavity sections.

While we have shown and described several embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art and we therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims.

We claim:

1. Apparatus for imparting adjusting movements to a movable member,comprising:

an actuating cylinder,

an actuating piston slidably disposed in said cylinder,

one of said actuating cylinder and actuating piston including means forconnecting same to said movable member for movement therewith,

a control chamber communicating with a first face of said actuatingpiston such that supply of fluid under pressure to said control chambereffects movement of said actuating piston in a first direction anddrainage of fluid from said control chamber perm its movement of saidactuating piston in a second direction opposite said first direction,

control chamber inlet means for communicating fluid under pressure tosaid control chamber,

control chamber exhaust means for exhausting fluid from said controlchamber,

a control valve for controlling the opening and closing of said controlchamber inlet and exhaust means, said control valve including a controlvalve member acted upon in one direction by a fluid control pressure andin the other opposite direction by a control biasing force,

said actuating piston including a cavity bounded in part by a generatingsurface which is spaced from a centerline of said actuating piston byvarying amounts along the length of said actuating piston, andinterconnecting means in contact with both said control valve member andsaid generating surface for effecting changes in said control biasingforce as a function of the position of said actuating piston along thetravel path thereof in said actuating cylinder.

2. Apparatus according to claim 1, wherein said cavity forms part ofsaid control chamber, wherein a second face of said actuating pistonwhich faces oppositely of and is smaller than said first face iscontinuously communicated with the fluid under pressure supplied to saidcontrol chamber inlet means, wherein said fluid under pressure is ahydraulic fluid,

wherein said interconnecting means is an elastically bendable two-armedlever having one arm thereof in contact with said control valve memberand the other arm thereof in contact with said generating surface, andwherein said two-armed lever is supported intermediate the ends thereofat a part fixed with said actuating cylinder so as to apply an elasticstressing force as said control biasing force.

3. Apparatus according to claim 2, wherein said control valve member isconstrained to move transversely to the direction of movement of saidactuating piston.

4. Apparatus according to claim 3, wherein said control valve meansincludes means for opening one of said control chamber inlet and exhaustmeans upon minimal movement of said control valve member from a centralposition thereof.

5. Apparatus according to claim 4, wherein said movable member is aguide vane of a gas turbine engine or the like.

6. Apparatus according to claim 1, wherein the inclination of thegenerating surface relative to the centerline of the actuating piston:is relatively great near one end of the cavity to define a drive range,is relatively small along an intermediate portion of the cavity, and isrelatively great at the end of the cavity opposite said one end todefine a deceleration range.

7. Apparatus according to claim 5, wherein the inclination of thegenerating surface relative to the centerline of the actuating piston:is relatively great near one end of the cavity to define a drive range,is relatively small along an intermediate portion of the cavity, and isrelatively great at the end of the cavity opposite said one end todefine a deceleration range.

8. Apparatus according to claim 2, wherein the inclination of thegenerating surface relative to the centerline of the actuating piston:is relatively great near one end of the cavity to define a drive range.is relatively small along an intermediate portion of the cavity, and isrelatively great at the end of the cavity opposite said one end todefine a deceleration range.

9. Apparatus according to claim 2, wherein said control valve member isconstructed with cylindrical valve member end portions at the endsthereof having control edges for controlling openings of said controlchamber inlet and exhaust means. said control edges being located at thejuncture of said end portions with a central portion of said controlvalve member which has a smaller diameter than either of said endportions such that the annulus formed around said central portion formspart of the control chamber.

10. Apparatus according to claim 8, wherein said control valve member isconstructed with cylindrical valve member end portions at the endsthereof having control edges for controlling openings of said controlchamber inlet and exhaust means, said control edges being located at thejuncture of said end portions with a central portion of said controlvalve member which has a smaller diameter than either of said endportions such that the annulus formed around said central portion formspart of the control chamber.

11. Apparatus according to claim 2, wherein said control valve memberhas an inlet control edge at one end and an exhaust control edge at theother end, wherein said control chamber communicates with said controlvalve member by an opening having a width in the direction of movementof said control valve member which is the same as the distance betweensaid inlet and exhaust control edges, and wherein a control cylinderwithin which said control valve member is slidably guided exhibits anuncontrolled inlet duct and an uncontrolled exhaust duct at respectiveopposite axial sides of said opening with respect to movement of saidcontrol valve member.

12. Apparatus according to claim 11, wherein said uncontrolled inletduct communicates with a pressure line and said uncontrolled exhaustduct communicates with a drain line.

13. Apparatus according to claim 8, wherein said control valve memberhas an inlet control edge at one end and an exhaust control edge at theother end, wherein said control chamber communicates with said controlvalve member by an opening having a width in the direction of movementof said control valve member which is the same as the distance betweensaid inlet and exhaust control edges, and wherein a control cylinderwithin which said control valve member is slidably guided exhibits anuncontrolled inlet duct and an uncontrolled exhaust duct at respectiveopposite axial sides of said opening with respect to movement of saidcontrol valve member.

14. Apparatus according to claim 2, wherein the one arm of said lever isof forked configuration with two spaced fork parts, wherein said controlvalve member is flattened on two opposite sides to accommodate saidcontact of said fork parts in said flattened sides in a longitudinalcenter plane of the control valve member.

15. Apparatus according to claim 8, wherein the one arm of said lever isof forked configuration with two spaced fork parts, and wherein saidcontrol valve member is flattened on two opposite sides to accommodatesaid contact of said fork parts in said flattened sides in alongitudinal center plane of the control valve member.

16. Apparatus according to claim 9, wherein the one arm of said lever isof forked configuration with two spaced fork parts, and wherein saidcontrol valve member is flattened on two opposite sides to accommodatesaid contact of said fork parts in said flattened sides in alongitudinal center plane of the control valve member.

17. Apparatus according to claim 11, wherein the one arm of said leveris of forked configuration with two spaced fork parts, and wherein saidcontrol valve member is flattened on two opposite sides to accommodatesaid contact of said fork parts in said flattened sides in alongitudinal center plane of the control valve member.

18. Apparatus according to claim 2, wherein a restrictor ductcommunicates said control chamber inlet means with a face of saidcontrol valve member acted upon by said fluid control pressure, andwherein said last-mentioned face of said control valve member isarranged in direct fluid communication with a mechanism for controllingthe magnitude of said fluid control pressure, said mechanism includingmeans operable by a variable electromagnetic force to vary saidmagnitude of said fluid control pressure.

19. Apparatus according to claim 8, wherein a restrictor ductcommunicates said control chamber inlet means with a face of saidcontrol valve member acted upon by said fluid control pressure, andwherein said last-mentioned face of said control valve member isarranged in direct fluid communication with a mechanism for controllingthe magnitude of said fluid control pressure, said mechanism includingmeans operable by a variable electromagnetic force to vary saidmagnitude of said fluid control pressure.

20. Apparatus according to claim 9, wherein a restrictor ductcommunicates said control chamber inlet means with a face of saidcontrol valve member acted upon by said fluid control pressure, andwherein said last-mentioned face of said control valve member isarranged in direct fluid communication with a mechanism for controllingthe magnitude of said fluid control pressure, said mechanism includingmeans operable by a variable electromagnetic force to vary saidmagnitude of said fluid control pressure.

2]. Apparatus according to claim 11, wherein a restrictor ductcommunicates said control chamber inlet means with a face of saidcontrol valve member acted upon by said fluid control pressure, andwherein said last-mentioned face of said control valve member isarranged in direct fluid communication with a mechanism for controllingthe magnitude of said fluid control pressure, said mechanism includingmeans operable by a variable electromagnetic force to vary saidmagnitude of said fluid control pressure.

22. Apparatus according to claim 18, wherein said mechanism controls adrain for varying the back pressure build up from the fluid communicatedby said restrictor duct to said face of said control valve member.

23. Apparatus according to claim 2, wherein said control valve includesa control valve cylinder for accommodating sliding movement of saidcontrol valve member, and wherein a damping duct communicates saidcontrol chamber exhaust means with a face of said control valve memberwhich faces oppositely to the face of said control valve member which isacted upon by said fluid control pressure.

24. Appararatus according to claim 8, wherein said control valveincludes a control valve cylinder for accommodating sliding movement ofsaid control valve member, and wherein a damping duct communicates saidcontrol chamber exhaust means with a face of said control valve memberwhichfaces oppositely to the face of said control valve member which isacted upon by said fluid control pressure.

25. Apparatus according to claim 9, wherein said control valve includesa control valve cylinder for accommodating sliding movement of saidcontrol valve member, and wherein a damping duct communicates saidcontrol chamber exhaust means with a face of said control valve memberwhich faces oppositely to the face of said control valve member which isacted upon by said fluid control pressure.

26. Apparatus, according to claim 11, wherein said control valveincludes a control valve cylinder for accommodating sliding movement ofsaid control valve member, and wherein a damping duct communicates saidcontrol chamber exhaust means with a face of said control valve memberwhich faces oppositely to the face of said control valve member which isacted upon by said fluid control pressure.

27. Apparatus according to claim 18, wherein said control valve includesa control valvecylinder for accommodating sliding movement of saidcontrol valve member, and wherein a damping duct communicates saidcontrol chamber exhaust means with a face of said control valve memberwhich faces oppositely to the face of said control valve member which isacted upon by said fluid control pressure.

28. Apparatus according to claim 2, wherein said control valve includesa bushing inserted into a hollow portion of an actuator housing fixedwith said actuating cylinder, said control valve member being slidableinside of said bushing, said bushing being radially spaced from internalwalls of said hollow portion by sealing rings,

29. Apparatus according to claim 28, wherein said bushing is of steppeddiameter with the maximum diameter at an end thereof which is axiallyfixed to said actuator housing, whereby axial insertion of said bushingand sealing rings is accommodated.

30. Apparatus according to claim 8, wherein said control valve includesa bushing inserted into a hollow portion of an actuator housing fixedwith said actuating cylinder, said control valve member being slidableinside of said bushing, said bushing being radially spaced from internalwalls of said hollow portion by sealing rings.

31. Apparatus according to claim 9, wherein said control valve includesa bushing inserted into a hollow portion of an actuator housing fixedwith said actuating cylinder, said control valve member being slidableinside of said bushing, said bushing being radially spaced from internalwalls of said hollow portion by sealing rings.

32. Apparatus according to claim 11, wherein said control valve includesa bushing inserted into a hollow portion of an actuator housing fixedwith said actuating cylinder, said control valve member being slidableinside of said bushing, said bushing being radially spaced from internalwalls of said hollow portion by sealing rings.

33. Apparatus according to claim 18, wherein said control valve includesa bushing inserted into a hollow portion of an actuator housing fixedwith said actuating cylinder, said control valve member being slidableinside of said bushing, said bushing radially spaced from internal wallsof said hollow portion by sealing rings.

34. Apparatus according to claim 23, wherein said control valve includesa bushing inserted into a hollow portion of an actuator housing fixedwith said actuating cylinder, said control valve member being slidableinside of said bushing, said bushing being radially spaced from internalwalls of said hollow portion by sealing rings.

35. Apparatus according to claim 8, wherein the inclination of thegenerating surface relative to the centerline of the actuating piston isgreater in said deceleration range than in said drive range.

l U l

1. Apparatus for imparting adjusting movements to a movable member,comprising: an actuating cylinder, an actuating piston slidably disposedin said cylinder, one of said actuating cylinder and actuating pistonincluding means for connecting same to said movable member for movementtherewith, a control chamber communicating with a first face of saidactuating piston such that supply of fluid under pressure to saidcontrol chamber effects movement of said actuating piston in a firstdirection and drainage of fluid from said control chamber perm itsmovement of said actuating piston in a second direction opposite saidfirst direction, control chamber inlet means for communicating fluidunder pressure to said control chamber, control chamber exhaust meansfor exhausting fluid from said control chamber, a control valve forcontrolling the opening and closing of said control chamber inlet andexhaust means, said control valve including a control valve member actedupon in one direction by a fluid control pressure and in the otheropposite direction by a control biasing force, said actuating pistonincluding a cavity bounded in part by a generating surface which isspaced from a centerline of said actuating piston by varying amountsalong the length of said actuating piston, and interconnecting means incontact with both said control valve member and said generating surfacefor effecting changes in said control biasing force as a function of theposition of said actuating piston along the travel path thereof in saidactuating cylinder.
 2. Apparatus according to claim 1, wherein saidcavity forms part of said control chamber, wherein a second face of saidactuating piston which faces oppositely of and is smaller than saidfirst face is continuously communicated with the fluid under pressuresupplied to said control chamber inlet means, wherein said fluid underpressure is a hydraulic fluid, wherein said interconnecting means is anelastically bendable two-armed lever having one arm thereof in contactwith said control valve member and the othEr arm thereof in contact withsaid generating surface, and wherein said two-armed lever is supportedintermediate the ends thereof at a part fixed with said actuatingcylinder so as to apply an elastic stressing force as said controlbiasing force.
 3. Apparatus according to claim 2, wherein said controlvalve member is constrained to move transversely to the direction ofmovement of said actuating piston.
 4. Apparatus according to claim 3,wherein said control valve means includes means for opening one of saidcontrol chamber inlet and exhaust means upon minimal movement of saidcontrol valve member from a central position thereof.
 5. Apparatusaccording to claim 4, wherein said movable member is a guide vane of agas turbine engine or the like.
 6. Apparatus according to claim 1,wherein the inclination of the generating surface relative to thecenterline of the actuating piston: is relatively great near one end ofthe cavity to define a drive range, is relatively small along anintermediate portion of the cavity, and is relatively great at the endof the cavity opposite said one end to define a deceleration range. 7.Apparatus according to claim 5, wherein the inclination of thegenerating surface relative to the centerline of the actuating piston:is relatively great near one end of the cavity to define a drive range,is relatively small along an intermediate portion of the cavity, and isrelatively great at the end of the cavity opposite said one end todefine a deceleration range.
 8. Apparatus according to claim 2, whereinthe inclination of the generating surface relative to the centerline ofthe actuating piston: is relatively great near one end of the cavity todefine a drive range, is relatively small along an intermediate portionof the cavity, and is relatively great at the end of the cavity oppositesaid one end to define a deceleration range.
 9. Apparatus according toclaim 2, wherein said control valve member is constructed withcylindrical valve member end portions at the ends thereof having controledges for controlling openings of said control chamber inlet and exhaustmeans, said control edges being located at the juncture of said endportions with a central portion of said control valve member which has asmaller diameter than either of said end portions such that the annulusformed around said central portion forms part of the control chamber.10. Apparatus according to claim 8, wherein said control valve member isconstructed with cylindrical valve member end portions at the endsthereof having control edges for controlling openings of said controlchamber inlet and exhaust means, said control edges being located at thejuncture of said end portions with a central portion of said controlvalve member which has a smaller diameter than either of said endportions such that the annulus formed around said central portion formspart of the control chamber.
 11. Apparatus according to claim 2, whereinsaid control valve member has an inlet control edge at one end and anexhaust control edge at the other end, wherein said control chambercommunicates with said control valve member by an opening having a widthin the direction of movement of said control valve member which is thesame as the distance between said inlet and exhaust control edges, andwherein a control cylinder within which said control valve member isslidably guided exhibits an uncontrolled inlet duct and an uncontrolledexhaust duct at respective opposite axial sides of said opening withrespect to movement of said control valve member.
 12. Apparatusaccording to claim 11, wherein said uncontrolled inlet duct communicateswith a pressure line and said uncontrolled exhaust duct communicateswith a drain line.
 13. Apparatus according to claim 8, wherein saidcontrol valve member has an inlet control edge at one end and an exhaustcontrol edge at the other end, wherein said control chamber communicateswith said control valve member by an opening having a width in tHedirection of movement of said control valve member which is the same asthe distance between said inlet and exhaust control edges, and wherein acontrol cylinder within which said control valve member is slidablyguided exhibits an uncontrolled inlet duct and an uncontrolled exhaustduct at respective opposite axial sides of said opening with respect tomovement of said control valve member.
 14. Apparatus according to claim2, wherein the one arm of said lever is of forked configuration with twospaced fork parts, wherein said control valve member is flattened on twoopposite sides to accommodate said contact of said fork parts in saidflattened sides in a longitudinal center plane of the control valvemember.
 15. Apparatus according to claim 8, wherein the one arm of saidlever is of forked configuration with two spaced fork parts, and whereinsaid control valve member is flattened on two opposite sides toaccommodate said contact of said fork parts in said flattened sides in alongitudinal center plane of the control valve member.
 16. Apparatusaccording to claim 9, wherein the one arm of said lever is of forkedconfiguration with two spaced fork parts, and wherein said control valvemember is flattened on two opposite sides to accommodate said contact ofsaid fork parts in said flattened sides in a longitudinal center planeof the control valve member.
 17. Apparatus according to claim 11,wherein the one arm of said lever is of forked configuration with twospaced fork parts, and wherein said control valve member is flattened ontwo opposite sides to accommodate said contact of said fork parts insaid flattened sides in a longitudinal center plane of the control valvemember.
 18. Apparatus according to claim 2, wherein a restrictor ductcommunicates said control chamber inlet means with a face of saidcontrol valve member acted upon by said fluid control pressure, andwherein said last-mentioned face of said control valve member isarranged in direct fluid communication with a mechanism for controllingthe magnitude of said fluid control pressure, said mechanism includingmeans operable by a variable electromagnetic force to vary saidmagnitude of said fluid control pressure.
 19. Apparatus according toclaim 8, wherein a restrictor duct communicates said control chamberinlet means with a face of said control valve member acted upon by saidfluid control pressure, and wherein said last-mentioned face of saidcontrol valve member is arranged in direct fluid communication with amechanism for controlling the magnitude of said fluid control pressure,said mechanism including means operable by a variable electromagneticforce to vary said magnitude of said fluid control pressure. 20.Apparatus according to claim 9, wherein a restrictor duct communicatessaid control chamber inlet means with a face of said control valvemember acted upon by said fluid control pressure, and wherein saidlast-mentioned face of said control valve member is arranged in directfluid communication with a mechanism for controlling the magnitude ofsaid fluid control pressure, said mechanism including means operable bya variable electromagnetic force to vary said magnitude of said fluidcontrol pressure.
 21. Apparatus according to claim 11, wherein arestrictor duct communicates said control chamber inlet means with aface of said control valve member acted upon by said fluid controlpressure, and wherein said last-mentioned face of said control valvemember is arranged in direct fluid communication with a mechanism forcontrolling the magnitude of said fluid control pressure, said mechanismincluding means operable by a variable electromagnetic force to varysaid magnitude of said fluid control pressure.
 22. Apparatus accordingto claim 18, wherein said mechanism controls a drain for varying theback pressure build up from the fluid communicated by said restrictorduct to said face of said control valve member.
 23. Apparatus accordingto claim 2, wherein said control valve includes a control valve cylinderfor accommodating sliding movement of said control valve member, andwherein a damping duct communicates said control chamber exhaust meanswith a face of said control valve member which faces oppositely to theface of said control valve member which is acted upon by said fluidcontrol pressure.
 24. Appararatus according to claim 8, wherein saidcontrol valve includes a control valve cylinder for accommodatingsliding movement of said control valve member, and wherein a dampingduct communicates said control chamber exhaust means with a face of saidcontrol valve member which faces oppositely to the face of said controlvalve member which is acted upon by said fluid control pressure. 25.Apparatus according to claim 9, wherein said control valve includes acontrol valve cylinder for accommodating sliding movement of saidcontrol valve member, and wherein a damping duct communicates saidcontrol chamber exhaust means with a face of said control valve memberwhich faces oppositely to the face of said control valve member which isacted upon by said fluid control pressure.
 26. Apparatus according toclaim 11, wherein said control valve includes a control valve cylinderfor accommodating sliding movement of said control valve member, andwherein a damping duct communicates said control chamber exhaust meanswith a face of said control valve member which faces oppositely to theface of said control valve member which is acted upon by said fluidcontrol pressure.
 27. Apparatus according to claim 18, wherein saidcontrol valve includes a control valve cylinder for accommodatingsliding movement of said control valve member, and wherein a dampingduct communicates said control chamber exhaust means with a face of saidcontrol valve member which faces oppositely to the face of said controlvalve member which is acted upon by said fluid control pressure. 28.Apparatus according to claim 2, wherein said control valve includes abushing inserted into a hollow portion of an actuator housing fixed withsaid actuating cylinder, said control valve member being slidable insideof said bushing, said bushing being radially spaced from internal wallsof said hollow portion by sealing rings.
 29. Apparatus according toclaim 28, wherein said bushing is of stepped diameter with the maximumdiameter at an end thereof which is axially fixed to said actuatorhousing, whereby axial insertion of said bushing and sealing rings isaccommodated.
 30. Apparatus according to claim 8, wherein said controlvalve includes a bushing inserted into a hollow portion of an actuatorhousing fixed with said actuating cylinder, said control valve memberbeing slidable inside of said bushing, said bushing being radiallyspaced from internal walls of said hollow portion by sealing rings. 31.Apparatus according to claim 9, wherein said control valve includes abushing inserted into a hollow portion of an actuator housing fixed withsaid actuating cylinder, said control valve member being slidable insideof said bushing, said bushing being radially spaced from internal wallsof said hollow portion by sealing rings.
 32. Apparatus according toclaim 11, wherein said control valve includes a bushing inserted into ahollow portion of an actuator housing fixed with said actuatingcylinder, said control valve member being slidable inside of saidbushing, said bushing being radially spaced from internal walls of saidhollow portion by sealing rings.
 33. Apparatus according to claim 18,wherein said control valve includes a bushing inserted into a hollowportion of an actuator housing fixed with said actuating cylinder, saidcontrol valve member being slidable inside of said bushing, said bushingradially spaced from internal walls of said hollow portion by sealingrings.
 34. Apparatus according to claim 23, wherein said control valveincludes a bushing inserted into a hollow portion of an actuator housingfixed with said actuating cylinder, said control vaLve member beingslidable inside of said bushing, said bushing being radially spaced frominternal walls of said hollow portion by sealing rings.
 35. Apparatusaccording to claim 8, wherein the inclination of the generating surfacerelative to the centerline of the actuating piston is greater in saiddeceleration range than in said drive range.